I’ve got a 1962 ford 4000 gas burner that recently acquired. It’s a great old tractor but I’m not getting much fuel from the tank. Looking into the tank I don’t see a lot of rust but I do see a spring loaded screw. Don’t have a screwdriver long enough to try to mess with it at home. Was wondering if any of you guys have had a similar issue Is that a screw that can change the flow?